Java/JSP/Beans
Содержание
- 1 Bean property display
- 2 Here are the EmailBean properties
- 3 Beans with scriptlet
- 4 Calling a Private Method
- 5 Calling a Private Method
- 6 Getting a Property Value
- 6.1 JSP and Java beans 3
- 6.2 Please submit a valid stock symbol
- 6.3 Here is the latest value of <c:out value="${param.symbol}" />
- 6.4 JSP and Java beans (JavaBeans) 1
- 6.5 JSP and Java beans (JavaBeans) 2
- 6.6 JSP email valid check
- 6.7 Welcome
- 6.8 JSP Standard Actions: set property
- 6.9 JSP with Java bean
- 6.10 Set Property Value
- 6.11 Using a Constructor
- 7 Using a Constructor
- 8 Using a JavaBean
Bean property display
<source lang="java">
<%@ taglib uri="http://java.sun.ru/jstl/core" prefix="c" %> <jsp:useBean id="emailer" class="com.jexp.EmailBean"/> <jsp:setProperty name="emailer" property="*" /> <html> <head><title>Bean property display</title></head> <body>
Here are the EmailBean properties
SMTP host: <c:out value="${emailer.smtpHost}" />
Email recipient: <c:out value="${emailer.to}" />
Email sender: <c:out value="${emailer.from}" />
Email subject: <c:out value="${emailer.subject}" />
Email content: <c:out value="${emailer.content}" />
</body>
</html>
</source>
Beans with scriptlet
<source lang="java">
<%@ page import="com.jexp.Book" %> <%
Book myBook = (Book) session.getAttribute("myBookBean");
if ( myBook == null)
{
myBook = new Book();
myBook.setAuthor("Joe");
session.setAttribute("myBookBean", myBook);
} // end of if ()
%>
<html>
<head><title>JavaBean usage with scriptlets (1)</title></head> <body>This page creates a JavaBean if you don"t already have one.
Click to go to a page that retrieves it. </body>
</html> //useAndSet2.jsp <html>
<head><title>JavaBean usage - getProperty tag</title></head> <body>This page retrieves a JavaBean, and its properties.
| JavaBean property | Value |
|---|---|
| id | <jsp:getProperty name="myBookBean" property="id" /> |
| title | <jsp:getProperty name="myBookBean" property="title" /> |
| author | <jsp:getProperty name="myBookBean" property="author" /> |
| price | <jsp:getProperty name="myBookBean" property="price" /> |
</body>
</html>
</source>
Calling a Private Method
<source lang="java">
// JSP file <HTML>
<HEAD>
<TITLE>Calling a Private Method</TITLE>
</HEAD>
<BODY>
Calling a Private Method
<jsp:useBean id="bean1" class="beans.Message" />
The message is: <jsp:getProperty name="bean1" property="message" />
<jsp:setProperty name="bean1" property="message" value="Hello again!" />
Now the message is: <jsp:getProperty name="bean1" property="message" />
</BODY>
</HTML>
/////////////////////////////////////// //Java Source Code package beans; import java.io.Serializable; public class Message implements Serializable {
private String message = "Hello from JSP!";
public void setMessage(String m)
{
this.message = m;
}
public String getMessage()
{
return privateMessage();
}
private String privateMessage()
{
return this.message;
}
public Message()
{
}
}
</source>
Get Set Properties JSTL
<source lang="java">
//File: index.jsp <html>
<head>
<title>Using a JavaBean</title>
</head>
<body>
Using a JavaBean
<jsp:useBean id="myCar" class="beans.CarBean" /> I have a <jsp:getProperty name="myCar" property="make" />
<jsp:setProperty name="myCar" property="make" value="Ferrari" /> Now I have a <jsp:getProperty name="myCar" property="make" /> </body>
</html>
////////////////////////////////////////////////////////////// //Java Bean package beans; import java.io.Serializable; public class CarBean implements Serializable {
private String make = "Company";
private double cost = 100.00;
private double taxRate = 17.5;
public CarBean() {}
public String getMake()
{
return make;
}
public void setMake(String make)
{
this.make = make;
}
public double getPrice()
{
double price = (cost + (cost * (taxRate/100)));
return price;
}
}
</source>
Getting a Property Value
<source lang="java">
//File: index.jsp <HTML>
<HEAD> <TITLE>Getting a Property Value</TITLE> </HEAD> <BODY>
Getting a Property Value
<jsp:useBean id="bean1" class="beans.Message" /> The message is: <jsp:getProperty name="bean1" property="message" /> </body>
</html>
//////////////////////////////////////////// //Java Bean Class package beans; public class Message {
private String message = "Hello from JSP!";
public String getMessage()
{
return message;
}
public Message()
{
}
}
</source>
JSP and Java beans 3
<source lang="java">
/* <%@ taglib uri="http://java.sun.ru/jstl/core" prefix="c" %> <jsp:useBean id="priceFetcher" class="com.jexp.StockPriceBean" /> <html> <head><title>Price Fetch</title></head> <body> <c:choose>
<c:when test="${empty param.symbol}">
Please submit a valid stock symbol
<form method="POST" action ="<c:out value="${pageContext.request.contextPath}" />/priceFetch.jsp">
| Stock symbol: | <input type="text" name="symbol" size="10"> |
| <input type="submit" value="Submit Info"> |
</c:when> <c:otherwise>
Here is the latest value of <c:out value="${param.symbol}" />
<jsp:setProperty name="priceFetcher" property="symbol" value="<%= request.getParameter(\"symbol\") %>" />
<jsp:getProperty name="priceFetcher" property="latestPrice"/>
</c:otherwise>
</c:choose>
</body> </html>
- /
package com.jexp; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.net.URL; import java.net.MalformedURLException; import javax.swing.text.html.HTMLEditorKit.ParserCallback; import javax.swing.text.MutableAttributeSet; import javax.swing.text.html.parser.ParserDelegator; public class StockPriceBean {
/**
* The URL base for requesting a stock price; it looks like
* "http://finance.yahoo.ru/q?d=t&s="
*/
private static final String urlBase = "http://finance.yahoo.ru/q?d=t&s=";
/**
* The character stream of HTML that is parsed for the stock price
* returned by java.net.URL.openStream()
*
* see java.net.URL
* @see java.io.BufferedReader
*/
private BufferedReader webPageStream = null;
/**
* The java.net.URL object that represents the stock Web page
*
*/
private URL stockSite = null;
/**
* The ParserDelegator object for which ParserDelegator.parse() is
* called for the Web page
*
* @see javax.swing.text.html.parser.ParserDelegator
*/
private ParserDelegator htmlParser = null;
/**
* The MyParserCallback object (inner class); this object is an
* argument to the ParserDelegator.parse() method
*
* @see javax.swing.text.html.HTMLEditorKit.ParserCallback
*/
private MyParserCallback callback = null;
/**
* This String holds the HTML text as the Web page is parsed.
*
* @see MyParserCallback
*/
private String htmlText = "";
private String symbol = "";
private float stockVal = 0f;
//A JavaBean has to have a no-args constructor (we explicitly show this
//constructor as a reminder; the compiler would have generated a default
//constructor with no arguments automatically
public StockPriceBean() {}
//Setter or mutator method for the stock symbol
public void setSymbol(String symbol){
this.symbol = symbol;
}
class MyParserCallback extends ParserCallback {
//bread crumbs that lead us to the stock price
private boolean lastTradeFlag = false;
private boolean boldFlag = false;
public MyParserCallback(){
//Reset the enclosing class" instance variable
if (stockVal != 0)
stockVal = 0f;
}
public void handleStartTag(javax.swing.text.html.HTML.Tag t,
MutableAttributeSet a,int pos) {
if (lastTradeFlag && (t == javax.swing.text.html.HTML.Tag.B )){
boldFlag = true;
}
}//handleStartTag
public void handleText(char[] data,int pos){
htmlText = new String(data);
//System.out.println(htmlText);
if (htmlText.indexOf("No such ticker symbol.") != -1){
throw new IllegalStateException(
"Invalid ticker symbol in handleText() method.");
} else if (htmlText.equals("Last Trade:")){
lastTradeFlag = true;
} else if (boldFlag){
try{
stockVal = new Float(htmlText).floatValue();
} catch (NumberFormatException ne) {
try{
// tease out any commas in the number using
//NumberFormat
java.text.NumberFormat nf = java.text.NumberFormat.
getInstance();
Double f = (Double) nf.parse(htmlText);
stockVal = (float) f.doubleValue();
} catch (java.text.ParseException pe){
throw new IllegalStateException(
"The extracted text " + htmlText +
" cannot be parsed as a number!");
}//try
}//try
lastTradeFlag = false;
boldFlag = false;
}//if
} //handleText
}//MyParserCallback
public float getLatestPrice() throws IOException,MalformedURLException {
stockSite = new URL(urlBase + symbol);
webPageStream = new BufferedReader(new InputStreamReader(stockSite.
openStream()));
htmlParser = new ParserDelegator();
callback = new MyParserCallback();//ParserCallback
synchronized(htmlParser){
htmlParser.parse(webPageStream,callback,true);
}//synchronized
//reset symbol
symbol = "";
return stockVal;
}//getLatestPrice
}//StockPriceBean
</source>
JSP and Java beans (JavaBeans) 1
<source lang="java">
/* Beginning JavaServer Pages Vivek Chopra, Jon Eaves, Rupert Jones, Sing Li, John T. Bell ISBN: 0-7645-7485-X
- /
</source>
JSP and Java beans (JavaBeans) 2
<source lang="java">
/* Beginning JavaServer Pages Vivek Chopra, Jon Eaves, Rupert Jones, Sing Li, John T. Bell ISBN: 0-7645-7485-X
- /
</source>
JSP email valid check
<source lang="java">
//validCheck.jsp /* <%@page contentType="text/html"%> <%@ taglib uri="http://java.sun.ru/jstl/core" prefix="c" %> <jsp:useBean id="chk" class="com.jexp.ClientValidator" > <jsp:setProperty name="chk" property="*" /> </jsp:useBean> <%-- get valid property from ClientValidator bean --%> <c:set var="isValid" value="${chk.valid}" /> <c:if test="${isValid}">
<c:set var="email" value="${chk.email}" scope="request" />
<c:set var="password" value="${chk.password}" scope="request" />
</c:if> <html> <head><title>Client Checker</title></head> <body>
Welcome
Email:
<c:out value="${email}" />
Password:
<c:out value="${password}" />
</body> </html>
- /
package com.jexp; public class ClientValidator implements java.io.Serializable{ String email; String password; boolean valid; public ClientValidator(){
this.valid=false;}
public boolean isValid(){
/* Use a Data Access Object to validate the email and password.
If the validation does not fail then set this.valid to true*/
this.valid=true;
return valid;
}
public void setEmail(String _email){
if(_email != null && _email.length() > 0)
email = _email;
else
email = "Unknown";
} public String getEmail(){
return email; }
public void setPassword(String _password){
if(_password != null && _password.length() > 0)
password = _password;
else
password = "Unknown";
} public String getPassword(){
return password; }
}
</source>
JSP Standard Actions: set property
<source lang="java">
/* Beginning JavaServer Pages Vivek Chopra, Jon Eaves, Rupert Jones, Sing Li, John T. Bell ISBN: 0-7645-7485-X
- /
<html> <head> </head> <body>
<jsp:useBean id="myProduct" class="com.wrox.begjsp.ch03.Product"> <jsp:setProperty name="myProduct" property="sku" value="12345"/> <jsp:setProperty name="myProduct" property="name" value="DSL Modem"/> </jsp:useBean>
| Sku: | <%= myProduct.getSku() %> |
| Name: | ${myProduct.name} |
<jsp:useBean id="myMap" class="java.util.HashMap" /> <jsp:useBean id="myMap2" class="java.util.HashMap" type="java.util.Map"/>
</body>
</html>
</source>
JSP with Java bean
<source lang="java">
<%@ page import="java.util.*" %> <html>
<head>
<title>WishList</title>
<jsp:useBean class="com.jexp.WishList" id="wishList" scope="session"/>
<jsp:useBean class="com.jexp.WishListItems" id="wishListItems" scope="application" />
</head>
<body>
<% Enumeration e = request.getParameterNames(); %>
<% Set map = wishList.getMap(); %>
<% while(e.hasMoreElements()){
String key = (String)e.nextElement();
if(key.equals(wishListItems.getItem(0).getId())){
map.add(wishListItems.getItem(0));
}
if(key.equals(wishListItems.getItem(1).getId())){
map.add(wishListItems.getItem(1));
}
if(key.equals(wishListItems.getItem(2).getId())){
map.add(wishListItems.getItem(2));
}
if(key.equals(wishListItems.getItem(3).getId())){
map.add(wishListItems.getItem(3));
}
if(key.equals(wishListItems.getItem(4).getId())){
map.add(wishListItems.getItem(4));
}
} %>
Items currently In your Wish List:
<% if(map.size()==0){ %>
There are no items in your Wish List
<% }
else {
Set set = map; %>
<% if (set!=null){
com.jexp.Item[] keys = new com.jexp.Item[0];
keys = (com.jexp.Item[])set.toArray(keys);
for (int i=0;i<keys.length;i++){ %>
<%=keys[i].getName()%><%="
"%>
<% }
}
}%>
</body>
</html> package com.jexp; public class Item {
private String id;
private String name;
public Item(){}
public Item(String s, String t){
name=s;
id=t;
}
public String getId(){
return id;
}
public String getName(){
return name;
}
}
package com.jexp;
import javax.servlet.http.HttpSessionBindingListener;
import javax.servlet.http.HttpSessionBindingEvent;
import java.util.Set;
import java.util.HashSet;
import java.util.Iterator;
public class WishList implements HttpSessionBindingListener {
private Set map = new HashSet();
public Set getMap(){
return map;
}
//Session binding methods
public void valueBound(HttpSessionBindingEvent e){
System.out.println("The WishList has been Bound!");
}
public void valueUnbound(HttpSessionBindingEvent e){
Item[] keys = new Item[0];
System.out.println("Getting values...");
Iterator it = map.iterator();
while(it.hasNext()){
Item item = (Item)it.next();
System.out.println(item.getName());
}
}
}
package com.jexp; public class WishListItems {
private Item[] items = {
new Item("ID 1","Name 1"),
new Item("ID 2","Name 2"),
new Item("ID 3","Name 3"),
new Item("ID 4","Name 4"),
new Item("ID 5","Name 5")
};
public Item getItem(int i){
if (items[i]!=null){
return items[i];
}
else {
return null;
}
}
}
</source>
Set Property Value
Using a Constructor
<source lang="java">
//File: index.jsp <HTML>
<HEAD>
<TITLE>Using a Constructor</TITLE>
</HEAD>
<BODY>
Using a Constructor
<% beans.Message m = new beans.Message("Hello from JSP!"); %>
The message is: <%= m.msg() %>
</BODY>
</HTML>
/////////////////////////////////////////////////////////////////////////// //File: Message.java package beans; public class Message {
String msg;
public Message(String message)
{
msg = message;
}
public String msg() {
return msg;
}
}
</source>
Using a Java Bean Jsp
<source lang="java">
////////////////////////////////////// //File: index.jsp
<%@ page import="beans.MessageBean" %> <HTML>
<HEAD> <TITLE>Using a JavaBean</TITLE> </HEAD> <BODY>
Using a JavaBean
<% MessageBean m = new MessageBean(); %> The message is: <%= m.msg() %> </BODY>
</HTML> ////////////////////////////////////////////////// //File: MessageBean.java package beans;
public class MessageBean {
public MessageBean()
{
}
public String msg()
{
return "Hello from JSP!";
}
}
</source>
Using Bean Counter JSP
<source lang="java">
//File: BeanCounter.jsp <HTML> <HEAD> </HEAD> <BODY> <%@ page language="java" %> <jsp:useBean id="counter" scope="session" class="beans.Counter" /> <jsp:setProperty name="counter" property="count" param="count" /> <%
out.println("Count from scriptlet code : "
+ counter.getCount() + "
");
%> Count from jsp:getProperty :
<jsp:getProperty name="counter" property="count" />
</BODY> </HTML> /////////////////////////////////////////////////////////// //File: Counter.java package beans; import java.io.Serializable; public class Counter implements Serializable{
// Initialize the bean on creation
int count = 0;
// Parameterless Constructor
public Counter() {
}
// Property Getter
public int getCount() {
// Increment the count property, with every request
count++;
return this.count;
}
// Property Setter
public void setCount(int count) {
this.count = count;
}
}
</source>
